It was obviously a murder-suicide. That much is clear. The man, in his eighties, sent his family an e-mail saying there would be "no more pain and suffering." He stabbed his Alzheimer's afflicted wife once in the heart, then stabbed himself multiple times. This was a loving couple that didn't want to be separated. They didn't want to go to a nursing home and they knew the time was near. They'd rather die.
Just last September, in another small town not far away, an 86-year-old man shot his wife, called the police and then shot himself to death. The reasons are pretty much the same.